The present invention relates to a device for diagnosing an engine such as an internal combustion engine to detect an occurrence of trouble therein (hereinafter referred to merely as a trouble diagnosis device).
The arrangement of a conventional trouble diagnosis device of this type will be described with reference to FIG. 1 showing a circuit diagram therefor. Published Unexamined Japanese Patent Application No. Sho. 64-55605 discloses an example of such a conventional trouble diagnosis device as shown in FIG. 1.
The conventional trouble diagnosis device, as shown in FIG. 1, includes: a trouble diagnosis input unit 1; an over-heat input unit 2; an oil level input unit 3; an idle input unit 4; an engine control unit 5 having a microcomputer connected to those units 1 through 4; a trouble diagnosis display unit 6; an over-heat display unit 7; an oil level display unit 8; and an idle display unit 9, these units 6 through 9 being connected to the engine control unit 5.
The operation of the conventional trouble diagnosis device thus organized will be described.
When the trouble diagnosis input unit 1 is turned on, the engine control unit 5 enters a trouble diagnosis mode and performs a trouble diagnosis operation. Then, the unit 5 starts the diagnosis operation to locate the failure and causes the trouble diagnosis display unit 6 to display the position of the failure.
The above-described conventional trouble diagnosis device is disadvantageous in that, due to the provision of such trouble diagnosis input unit and the trouble diagnosis display unit as described above, it is difficult to simplify or miniaturize the device, and therefore the device is relatively high in manufacturing cost.